Type 1 is a router LSA. They are produced by every router and are flooded only within the area in which they originated.
Type 2 is a network LSA. They are produced by the DR and represents a pseudonode (virtual).
It lists all attached routers and is only flooded within originating area.
Type 3 is a Network summary LSA. They are produced by an ABR. They are sent into a single area to advertise destinations outside it.
Type 4 is an ASBR Summary LSA. They are produced by an ABR. They are the same as a type 3 but advertise the destination to an ASBR not a network. This will be a host address as it is a route to a router.
Type 5 is an AS External LSA . Produced by an ASBR and advertise external destinations (outside the OSPF AS) or a default route. They are flooded within the AS.
Type 7 is a NSSA External LSA. Originated by an ASBR within a not so stubby area. It is like a type 5 but instead of it being flooded within the AS it is only flooded within the NSSA where it came from.
I hope this is of help
please rate if so
Stu
